One method commonly used to apply informative or decorative material to a surface is screen printing. This method generally involves the use of a fine mesh screen stretched over a frame. The surface of the screen is provided with a pattern which corresponds to the informative or decorative material to be transferred to the surface of the object. A variety of techniques are known for producing such a screen, one example being to coat the screen material with a non-permeable photosensitive emulsion upon which the desired pattern can be exposed and processed. The frame serves as a reservoir for the ink or dye which is used in the printing process.
In order to use such a screen to apply a pattern to an object having a flat surface, the object to which the pattern is to be applied is generally positioned underneath and in close proximity to the prepared screen. A squeegee is then passed across the surface of the screen, and in particular, over that portion of the screen which is provided with the pattern to be applied to the object. As the squeegee advances across the screen, the ink or dye contained within the framed screen is caused to pass through those pores of the screen which define the pattern, which transfers the pattern from the screen to the surface of the object which is contacted by the screen, producing the desired printed image.
In order to use such a screen to apply a pattern to an object having a cylindrical surface, such as a bottle, a system of stationary, rotating chucks must often be used. In use, the cylindrical object is engaged by a chuck at each of its ends. For example, a bottle would generally be engaged at its base and its mouth. The chucked object is then positioned underneath and in close proximity to the prepared screen. A squeegee is simultaneously positioned on the opposing side of the screen, adjacent the curved outer surface of the bottle to which the pattern is to be applied. In this manner, the squeegee maintains contact between the bottle and the screen. The screen is then drawn across the curved outer surface of the object, while the object is permitted to rotate within the chuck. In so doing, the ink or dye contained within the framed screen is caused to pass through those pores of screen which define the pattern, which transfers the pattern from the screen to the surface of the cylindrical object, producing the desired printed image.
One example of such a process is disclosed in U.S. Pat. No. 3,518,939. In this disclosure, cylindrical bottles are mounted on a chuck and rotated over the top of a screen. The paint or dye is forced through the screen by a squeegee conveyor means which moves in an endless path of travel beneath the screen.
Such techniques, although effective, are seriously limited in the rate of production which they can attain. This is particularly so with regard to systems used to apply a pattern to cylindrical objects. The primary cause for this limitation in production rate relates to the need to separately insert and remove the objects from the chucks, the ability to print only one object at a time, and by the alternating motions required to set up the screen and squeegee for the next printing procedure.
In addition to the increase in production time, the use of a squeegee which continually passes over the screen, causes considerable wear to the screen, necessitating frequent replacement.
It is therefore extremely desirable to develop an apparatus and method for applying a printed pattern to a cylindrical object which obviates the foregoing limitations, and which accordingly permits a significant increase in the production rate.